Prior to the present invention, slackless rotary drawbar assemblies have been in wide spread use in the railroad industry for a number of years to couple one end of a railway car to an adjacent end of another car.
One such housing support member for a slackless rotary drawbar assembly is taught in U.S. Pat. No. 4,966,291 which is assigned to the assignee of the present invention. The disclosure of this patent is incorporated herein by reference thereto. With the arrangement taught in this prior art reference, free and cushioned slack is eliminated from the inner connection between cars. This slack elimination substantially minimizes undesirable longitudinal train action forces as well as the undesirable run in and run out of slack between adjacent cars during reversal of buff and draft train actions. This arrangement further minimizes the generation of large forces due to relative acceleration between the cars thereby reducing detrimental wear and damage to car components and lading. Obviously, reduction of wear and damage to such car components results in reduced maintenance cost and the reduction in damage to lading results in fewer damage claims which must be paid by the rail carrier.
Furthermore, the use of slackless rotary drawbar assemblies as a railcar coupling means has reduced the car weight by approximately 650 pounds. Such reduced car weight is achieved through elimination of the need for standard couplers, yokes, cushioning devices and striker bars. Such reduction in the weight of these cars translates into lower fuel consumption, and therefore, lower operating costs. Additionally, the elimination of various car components further reduces the maintenance cost associated with these components.
The draft load bearing surfaces of the housing support members of these prior art devices have, to the best of applicants' knowledge, always been formed as an integral part of the housing support member. This design results in the entire housing support member being manufactured from relatively expensive material in order to provide adequate wear resistance. Further, when these wear surfaces have been worn sufficiently it requires replacement of the entire housing support member, thus resulting in higher maintenance and equipment cost.
Another prior art housing support member for a slackless rotary drawbar assembly is taught in U.S. Pat. No. 5,000,330, the disclosure of which is also incorporated herein by reference. Even though the housing support member in this rotary drawbar assembly includes both a separate front portion and back portion, it suffers from the same wear problems as the housing support member taught in U.S. Pat. No. 4,966,291 discussed in detail above.